Corrosion of reinforcing bars and pre-stressed tendons is one of the most significant and unremitting factors related to the deterioration of bridges. Of approximately 500,000 bridges in the United States, about 80,000 of these are rated structurally deficient. Corrosion of bridge components is the underlying cause of many of the deficiency ratings, with many additional bridges showing early signs of imminently serious corrosion. In combination with water and oxygen, the main cause of corrosion is the chemical reaction of chloride ions originating from: (1) de-icing salts applied to roadways in regions where snow accumulation may be significant; or (2) saltwater that is commonly present in settings adjacent to marine environments. Chloride ions that penetrate concrete can react with underlying steel reinforcement. This reaction can expand the reinforcement and cause the overlying concrete to crack, spalling, and de-bond. This degradation may be further accelerated by vibration from traffic. The shield of the present invention is aimed at deterring the corrosive action of roadway solutions on the vertical surfaces—i.e. the splash zone. An additional threat to bridge infrastructure includes corrosion and deterioration of components within the pier cap area, which occurs below the road deck and at the top of the supporting column.
The pier cap area houses a bearing assembly. Bearing assemblies vary in their sizes and designs but typically consist of: (1) a pedestal that is anchored to the top of the pier cap; and (2) an overlying bearing that supports the underside of the road deck while accommodating limited structural movement. The bearing assembly and overall pier cap area is susceptible to corrosion and deterioration that mainly results from solutions entering the area from the above roadway. (An example of this is a salt solution that may bypass expansion joints within an overlying road deck.)
Typically, the pedestal is anchored to the top of the pier cap. As a result of the wicking effect from the roadway above, at the point of attachment, road solution may penetrate the concrete. This penetration propagates downward fracturing the concrete. Over time, the concrete is slowly eaten away thereby removing the static compressive surface that supports the bridge.